• Posted by: Eng. Donya Bino
• January 04, 2026

Email Spoofing Tools Behind Modern Attacks

Email spoofing is not a new threat.
What has changed is how quietly it succeeds.
Modern spoofing rarely depends on obvious fake addresses or poor language.
It relies on partial controls, routine workflows, and assumptions about trust.
For leadership, the risk is not a broken system.
It is confidence placed in controls that are incomplete.

What spoofing looks like in real incidents
In real organizations, spoofed emails often:
1. Use correct executive or partner names
2. Arrive during normal business activity
3. Align with real projects or payments
4. Pass basic technical checks
Many are delivered because, technically, they are allowed.

The tools behind modern email spoofing
Attackers do not rely on one method.
They test boundaries, adjust, and proceed where resistance is lowest.

Open source email frameworks
These tools allow attackers to control sender fields, headers, and timing.
Commonly observed
1. Sendmail
2. Postfix
3. Swaks
4. Custom Python scripts
swaks --to finance@company.com \
      --from ceo@company.com \
      --server mail.target.com

If authentication policies are weak or not enforced, this can succeed.

SMTP testing and address validation
The purpose of SMTP testing and address validation is to determine the existence of email addresses before sending actual messages to them. 
Attackers do this by using various tools, including smtp-user-enum, nmap SMTP scripts, and Telnet/OpenSSL. 
For example, an attacker may use the command, 
smtp-user-enum -M VRFY -U users.txt -t mail.company.com

to test the validity of email addresses and increase their credibility while reducing the amount of noise.

Domain look alike generation
Attackers automate domain impersonation.
Common tools
1. dnstwist
2. Custom domain mutation scripts
dnstwist company.com

Domains are often registered and used within hours.
They may not be detected until after an incident.

When Users view Headers and Display Names, most attacks focus on what users see.

Example:
Sender:  "Finance Director" <alerts@trusted-partner.com>
Reply To: payments@external-domain.com
Many mobile device users may only be able to see the name.

As Executive decision-makers depend on their familiarity with Emails, they tend to approve requests based on reputations, not based on headers.

Abuse of legitimate email services
Attackers use legitimate Email services to conduct their Attack, this may be achieved through the use of other legitimate Email platforms to gain confidence.
The following are examples of common platforms used by attackers:
1. Compromised Marketing Platforms.
2. Trial-based email providers.
3. Breached SaaS Tenants.
Messages arrive from domains that are difficult to block without business impact.

Bypassing incomplete SPF, DKIM, and DMARC
Most organizations have partial email authentication.
Attackers test what is enforced and adapt.
dig TXT _dmarc.company.com

A “none” or “quarantine” policy is often enough to proceed.

Campaign automation and follow ups
Modern spoofing is rarely one email.
Attackers automate:
1. Timing
2. Follow ups
3. Language refinement
4. Target selection
if no_reply_after_2_hours:
    send_followup("Just checking if you saw this")

Persistence, not sophistication, often closes the loop.

Real Life Examples
Example 1: CEO Request for Payment
1. An email with the name of the correct executive was used.
2. The request was made at the same time as a legitimate business transaction would have occurred.
3. The request was urgent, but still reasonable.
4. Finance quickly processed the payment.

 

 

Example 2: Supplier Redirecting Invoices
1. The attacker impersonated a long-time supplier.
2. Bank details were changed while the conversation was ongoing.
3. The tone of the email matched previous invoices.
4. The loss was discovered weeks after it occurred.

 

 

Example 3: Requesting Documents from HR
1. The email looked like it came from internal HR.
2. The email requested either tax or onboarding information.
3. Employees responded to the email as if it were legitimate.

 

 

Example 4: Impersonating Legal Counsel
1. The email was made to look like it was from an outside law firm.
2. The email requested that an urgent review of a document take place.
3. The contracts were sent without verification.

 

 

Example 5: Spoofing of Executives during Travel
1. The executive was publicly known to be traveling at that time.
2. The impersonator sent emails to the executive during the travel window.
3. The impersonator provided "limited connectivity" as a reason for the urgency of the request.
4. The executive granted approval for the request without verifying the information.

 

 

Example 6: Thread Hijacking
1. The attacker replied to an existing email thread.
2. The attacker was using a compromised external email account.
3. The conversation would have continued as it normally would.
4. The request would have blended naturally into the workflow.

 

 

How many companies are affected by spoofing?
Most email security systems have their primary focus on Malware or links.
Spoofing relies on Authority and Routine.

Most companies have common gaps in the following areas.
1. Lack of DMARC Enforcement
2. Use of Gateways as their only means of verifying emails
3. Informal Approval Process
4. Exceptions to established controls by executives
5. Email Security stops Malicious Code.
6. It doesn't protect against Misplaced Trust.

How does Spoofing affect the business beyond a direct financial loss
When a company experiences a spoofing event, it will often lead to:
1. An Audit Finding
2. An insurance dispute
3. Regulatory notice
4. A loss of confidence from partners
5. Freezing in Internal Processes
the overall disruption caused by a spoofing event exceeds the amount of financial theft.

What actions taken have materially reduced an Organizations’ Spoofing Risk?
Organizations that experience the lowest number of spoofing incidents are extremely clear and enforceable concerning their Security Policies and Practices.

Actions taken by companies to introduce effective safeguards against spoofing include:
1. DMARC Enforced with a Reject Policy
2. Mandatory verification of any Payments or Data Changes.
3. Specifically outlined communication rules for Executives.
4. Training and education that focuses on the Authority related misuse.
5. Monitoring and reporting of email authentication failures.
All of the actions taken as listed above are Governance Decisions rather than Technical Upgrades.

Questions leadership should ask
1. Is DMARC enforced or merely monitored?
2. Which requests bypass normal approvals?
3. How are urgent requests verified during travel or crises?
4. Are executives held to the same email rules?
5. How quickly can spoofing patterns be acted upon?
The answers often surface more risk than expected.

Modern email spoofing succeeds by exploiting trust, not technology.
Attackers do not need to break email systems.
They rely on people doing what they are used to doing.
Reducing this risk requires clear rules, enforced controls, and leadership alignment not more filters.